Synopsis: The diary extracts of a middle-aged man and his slightly younger wife. They secretly read each other's diaries, using them to make up for their lack of face-to-face communication, possibly brought on by reticence, although the book leaves several other possibilities open to speculation.
Written beautifully, 'The Key' is a pleasure to read from the first page to the last. Can be read on numerous levels, although anyone with an interest in psychoanalysis will probably find more than your average reader.
Taniazaki's most stunning achievement with this book is the way he takes a complex web of relationships, a lot of bizzare sexual and mental traits, ill health and death, and wraps them all into one reader-friendly ball.
Even as things seem to come to some sort of resolution in the last 30 pages, the smallest of threads are left dangling by Tanizaki, who leaves it up to the reader whether to paw them like a cat or leave them alone.
Although a concrete conclusion is suggested, many other conclusions remain equally valid. I won't say more here for fear of ruining the book.
One thing I will say is that, while one of the central themes of the novel is sex, it is not particularly explicit. 'The Key' seemed to be more about a middle-aged couple's relationship in general (and their relationship with their daughter), rather than specifically about their sex life (but then maybe sex is 'The Key' to the door of love?). Yes, there is a lot of sex, but the author does not flim-flam all over it in the way that Anais Nin does. If you are a bit prissy, I wouldn't imagine that you would be massively offended by this; if you want erotica, you'll probably feel pretty unsatisfied after this.